A Database for Triticeae and Avena
II. 22. Some characteristics for formation of quantity and quality
of the crop within hybrid populations of different generations of spring
G.F. Nikitenko, Research Agricultural Institute of Central Regions in
the Non-Chernozem Zone, Moscow-Nemchinovka, 143013, U.S.S.R.; M.A. Polukhin
and V.A. Gorshkova, Research Agricultural Institute of Central Chernozem
Regions named after V.V.Dokuchayev, 397463, Talovsky District, Voronezh
Development of a variety which is capable of producing high yields of
grain of good quality under different conditions, has always been a most
important objective in breeding of cereals. According to this fact the
yield of grain is considered to be the general criterion in breeding programs.
It is considered to be character which is to be stabilized, because yield
is the integrated sum of effects, acting in each case of environment factors,
in which potential possibilities of definite genotypes are manifested.
Superiority of heterozygotes as compared with homozygotes considering
resistance to environment conditions and reproduction of normal phenotype
provides heterozygotes with quite certain advantage which is used by hybrid
population. Therefore the up-to-date breeding programs involve in all cases
artificial crossing, because there is a widely spread opinion that hybridization
always produces a positive effect in characteristics and traits important
for national economy.
But as a matter of fact it is far from being like that. Breeding practice
proves that while crossing of highly valuable parents, the hybrids do not
possess these characters. And at the same time hybrids of high value often
result from crossing of parents which do not have these valuable characters.
One of the most important problems, therefore, in modern breeding is
the development of methods of precise identification of desirable genes,
resulting in high yields in parents and generations, i.e., in hybrid population.
As the result of long-term breeding activity with spring barley, we
have accumulated extensive experimental material on peculiarities of the
formation process in hybrid populations of different generations. The most
important results of this work are set forth below.
Since 1965, 20 hybrid combinations of spring barley have been developed
and studied. Their multiplication and testing was done by the Ohio method,
which allowed us to plant in the field all generations simultaneously by
1978: F1- F12 (Fig. 1). The sowing of 1978: F1 - in accordance with availability
of seeds, and F2 - F12 on plots of the 7m2 size with the nutrition
area for each plant - 15 x 3 cm. Productivity and its elements have been
studied as well as protein content in grain of three hybrid combinations.
Figure 1. Scheme of producing hybrid populations
of different generations.
The analysis of productivity of hybrid populations in different generations
(Table 1) shows that its level is different and it is increasing in later
generations. Thus, in combinations Europeum 353/133 x Nutans 187 the average
yield in F1 - F3 was 493.1 + 37.1 in the plot, and variation coefficient
(V%) - 13.0%, in F4 - F6 correspondingly 892 + 70.3 g, V - 13.6%
and in F7 - F12 - 973.3 + 43.8 g. and V - 11%. The same regularity
was observed in other crossing combinations as well - Spartan 11 x Nutans
187, Gerta x Nutans 187, but absolute values of productivity and its elements
Table 1. Productivity, protein content and component
of yield in hybrid populations of different generations (Europeum 353/133
x Nutans 187), 1978.
The diagram of the yielding capacity in F1 - F12 of Spartan 11 x Nutans
187 hybrid combination shows the same regularity - increase of the productivity
level from early to later generations of hybrid population. Thus, in F1
- F3 the yield (according to average data) was equal to 579.6 +
37.7 g, and V - 11.3%, and in the diagram its level is lower. In F4 - F6
the yield increases up to 752.3 + 47.7 g (V = 10.9%), and in F7
- F12 - up to 973.3 + 41.8 g (V = 11.3%) to which the highest upper
plateau corresponds in the diagram (Fig. 2).
Figure 2. Productivity and protein content in grain
of hybrid population of Spartan 11 x Nutans 187 of different generations
The results of the analysis of hybrid population yield in different
generations by elements of its structure permit to conclude that their
role in formation of the crop is different and depends mainly on traits
of parental forms, involved in combination of crossing. For instance, in
hybrid population Europeum 353/133 x Nutans 187 the yield increases in
generations due to productive branching and the mass of 1000 seeds, and
in Gerta hybrid x Nutans 187 - due to the mass of 1000 seeds.
Hybridological analysis of F1 - F12 plants proved that with the age
hybrid population involves specimen close to parental forms. Thus, if in
F2 of the combination Spartan 11 x Nutans 187 the plants with characters
of both parents were observed (with dense head but with smooth awns and
on the contrary - with loose head and notched awns), starting with F7 -
F8 there were the forms which prevailed in population, repitting the type
of initial parents (Table 2.).
Table 2. Results of hybridological analysis of the
plants of spring barley Spartan II x Nutans 187, 1978.
The change of protein content is of inverse character to the yield:
increased protein content corresponds to lower production of hybrid population
and on the contrary.
Summing up the above, it's possible to say that the increase of the
yield in hybrid population of spring barley, starting from early and to
the direction of later generations, is explained by main preconditions
of the hypothesis of genetic homeostasis and all consequences (Lerner,
1954). According to this hypothesis, under the effect of natural selection
genotypes are developed in the population. They provide with rather steady
reproduction of "optimum phenotype". As far as such an important trait
as yield, this homestasis means its stability under permanently changing
conditions of environment, which reflects the practical importance of this
phenomenon for plant breeding. In this case the structure of population
is modified in such a way that the balanced frequencies of alleles are
established, and they provide the hybrid population with the definite level
of heterozygosis, when adaptability of specimen, composing the population,
reaches the maximum in later generations.
The obtained experimental data are in contradiction with the assertion
of some authors, according to which the decrease of non-additive variance
is noted in comparison with the additive one with the age of hybrid population,
and in connection with this fact, expedience of selection of initial plants
in early generations is noted, for instance in F3 (Grafius et al., 1952),
and on the contrary, such selection is more effective in later generations
of the hybrid population, when its yield is getting more steady and higher
(Wiebe et al., 1968).
Grafius, J.E., W. L. Nelson, and V.A. Dirks. 1952. The heritability
of yield in barley as measured by early generation bulked progenies. Agron.
Lerner, C. M. 1954. Genetic homostasis. Edinburgh.
Wiebe, G. A. et al. 1968. Barley: Origin, botany, culture, winterhardiness,
genetics, utilization, pests. U.S. Department of Agriculture, Washington,
BGN 10 toc
BGN Main Index